Just to come back to the question a few pages back of whether he could have sold the idea separately from "Doctor Who".
In fact, RTD came up with the idea for a bunch of sexy alien-fighters a good few years ago - possibly, I think, before the return of Who was mooted and certainly before the involvement of Barrowman.
I don't know how many of the characters would have been the same, but I know it was going to be called "Excalibur" at that stage, and the once scene which survived from that version almost intact is the very first one from series 1 with a young policewoman watching a group of figures in dark coats reviving a murder victim with the Glove Of Revitalising And Doom.
Don't know why it didn't come off. Possibly TV wasn't ready - the climate was a lot less SF/fantasy friendly in the late 90s/early 2000s. Practically all the BBC did was "Invasion Earth" and "Crime Traveller" and they were underwhelming. ("Life On Mars", initially called "Ford Granada", had the same problem when they failed to sell it to C4 - an idea ahead of its time in 1997.) But when Who came back he dusted the idea off and gave it a re-spray, and linked in all the Who elements.
Just thought you'd all find that interesting!